In recent years, power storage devices such as lithium-ion secondary batteries, lithium-ion capacitors, and air cells have been developed.
As an active material of an electrode for the power storage device, for example, a material such as carbon or silicon is used. In the power storage device, these materials can occlude and release a reactive material (e.g., lithium ions). In addition, silicon (or phosphorus-doped silicon) has an advantage of larger theoretical capacity than carbon and larger capacity of a power storage device (e.g., Patent Document 1).